Lens-free imaging is an imaging technique based on holographic imaging. Interference patterns of objects are recorded and used to image cells. In large area lens-free imaging devices, a light source simultaneously illuminates multiple objects on a surface. Ideally, such a light source generates a planar light wavefront able to illuminate all objects simultaneously. To create such a planar wavefront, some devices use a light source that is positioned at a certain distance from the objects. Typically such a distance is in the order of 100 mm or more. This distance requirement prevents the lens-free device to be miniaturized and limits integration.